Some people think Witches Dancing at a Sabbath (La Danse du Sabbat) is Doré and some insist it isn't. This is made more difficult because many works signed by Doré are primarily works done by his apprentices under his direction so being true to type isn't the sole criteria. For example, for Rime of the Ancient Mariner, he had worked with some of his engravers so many times that he sketched the drawing directly on large woodblocks and the engravers completed the work. This is the other signature you see on many of the illustrations.

Doré did not sign the finished work unless it met with his approval, which could have been denied for any number of reasons. His signature does not appear on Witches Dancing at a Sabbath but his influence is still apparent.

A few years ago, I learned that a lot of Giger's stuff and a lot of Alex Gray's stuff wasn't done by them. They do rough sketches, but their apprentices do the rest. Then when it's complete, they just sign it and it gets sold as original.